Which is the longest tunnel in Italy?

Among highway tunnels, the Frejus ranks first

Alps and the Apennines: the two largest mountain chains in Italy, natural obstacles to mobility that have made it necessary to build infrastructure to facilitate the transport of people and goods. Over time, many tunnels have been excavated to overcome these natural barriers.

Some of them are for cars, others for trains: the objective, in any case, is to provide faster and more direct connections.
Where are these tunnels located in Italy? Some of the most important Italian tunnels have been built in collaboration with neighbouring countries: France,  Switzerland and Austria – great engineering works admired and studied worldwide.

But among the many tunnels in the country, which is the longest tunnel?

Longest motorway tunnels: the Frejus Tunnel in first place in Italy

The longest motorway tunnel in Italy is located under the Alps, on the border with France, connecting Bardonecchia in Val di Susa, and Modane, in the French Savoy. This is the Frejus Motoway Tunnel, which runs parallel to the railway tunnel of the same name. Managed by two companies, one French and one Italian, the tunnel was opened to traffic in 1980, more than a century after the railway tunnel was opened to traffic.
Its total length is 12.895 kilometres, enough to make it, in fact, the longest tunnel in Italy, albeit largely in French territory.

Second longest motorway tunnel in Italy: the Mont Blanc Tunnel

Even the second longest tunnel in Italy crosses the Alps, again linking Italy with France. It is the Mont Blanc Tunnel. Stretching between Chamonix, France, and Courmayeur in Italy’s Aosta Valley, it measures a total of 11.611 kilometres. Built jointly by France and Italy, it took eight years to build, between 1957 and 1965.
The tunnel passes under the highest peak of the Aiguilles de Chamonix on the Mont Blanc massif. Below the Aiguille du Midi, which is 3,842 metres above sea level, the mass of granite above the tunnel reaches 2,480 metres, a world record for motorway and railway tunnels.

The Gran Sasso: the third longest tunnel in Italy

Among the longest tunnels in Italy, just behind the two tunnels that connect Italy and France, is the Gran Sasso.
The third longest motorway tunnel in Italy measures a total of 10,190 metres - a length that places it just outside the world’s top 10 (12th place to be exact). First among the Apennine tunnels, it connects Assergi to Colledara, allowing a fast connection between the regions of Lazio and Abruzzo, passing below the Gran Sasso massif.
Moreover, it is the longest twin-tube motorway tunnel in Europe: the first tunnel in the direction of Teramo was excavated starting in the 1960s, based on a project by Alpina S.p.A., with the work entrusted to the CO.GE.FAR company. Its official opening was in 1984. The second tunnel, in the direction of Rome, was then opened in 1993. It should not be forgotten that next to the Gran Sasso tunnel are the laboratories of the Istituto Nazionale di Fisica Nucleare (INFN) (National Institute of Nuclear Physics), among the largest underground laboratories in the world.

Base Tunnel (Variante di Valico) and Sant’Antonio-Cepina Tunnel

In fourth place, among the longest motorway tunnels in Italy, is the Base Tunnel of the Variante di Valico (involving 66.6 kilometres of the Apennine section of the A1). Opened in December 2015, it is a double-arched tunnel with three lanes, 8.590 kilometres long and located in La Quercia-Aglio section of the Variante, an important work in making traffic between the north and south of the country more fluid.
Not to be forgetten is the Sant'Antonio-Cepina Tunnel, which is 7.895 kilometres long. Inaugurated in 2000, it is an alpine tunnel that forms part of the Stelvio State Road.

So these are the longest Italian motorway tunnels. In the country, however, there are also very long railway tunnels. Which of these extends for the greatest number of kilometres?

The longest railway tunnel in Italy: where is it?

In 2016, the Gotthard Base Tunnel was inaugurated in Switzerland. It is the longest high-speed railway tunnel in the world, reaching 57 kilometres. This immense work of Swiss engineering has surpassed the Seikan Tunnel in Japan, which with its 53 kilometres remains the longest underwater tunnel (although it must be said that the Channel Tunnel boasts a proper submarine route of 39 kilometres, compared with the 23 of the Seikan).

In Italy there are no railway tunnels of such length. No region has a tunnel that runs longer than 20 kilometres. At least for the time being. The Terzo Valico dei Giovi Tunnel - the name refers to the Tortona-Novi Ligure-Genoa rail line once it will be completed by 2022 - will be 27 kilometres long. The work - by the COCIV consortium led by Salini Impregilo – is in progress, with excavations proceeding with traditional and mechanised methods.

Longer railway tunnels: Sempione and Apennine Tunnels

With the Terzo Valico dei Giovi still under construction, the longest railway tunnel in Italy is the Sempione Tunnelbuilt by Italy and Switzerland between 1898 and 1905. Connecting the Val D'Ossola and Rhone Valley - passing under a peak of 3,552 metres above sea level at Mount Leone - measures 19.803 kilometres in the north-east tunnel and 19.823 kilometres in the south-west tunnel. Until the 1980s, it was the longest railway tunnel in the world.

To find the longest railway tunnel in Italy, it is necessary to move to the level of the Apennines, below which runs the Vaglia Tunnel: it must in fact be pointed out that, in the 79 kilometres of high-speed train line that connects Bologna and Florence, as many as 73 kilometres are in tunnels. The Vaglia Tunnel, for its part, is 18.711 kilometres long. It is therefore slightly longer than the Great Apennine Tunnel, 18.507 kilometres long, also located between Bologna and Florence. This tunnel was built between 1923 and 1934. At the time, it was the second largest in the world (immediately after the aforementioned Sempione).